Cefdinir of formula (I) above has a chemical name of 7.beta.-[2-(2-aminothiazol-4-yl)-2-(Z)-(hydroxyimino)acetamido]-3-vinyl-3- cep-hem-4-carboxylic acid. It is the third generation of cephalosporin antibiotics for oral administration and has a broader antibacterial spectrum over the general gram positive and gram negative bacteria than other antibiotics for oral administration. Particularly, it has been reported that cefdinir has an excellent antibacterial activity against Staphylococci and Streptococci.
In U.S. Pat. No. 4,559,334 is disclosed a process for preparing cefdinir as represented in the following reaction scheme 1. ##STR3##
In the above reaction, 7-amino-3-vinyl-3-cephem-4-carboxylic acid ester(A) is reacted with a reactive carboxylic acid derivative to obtain an 7-amido compound(B), and this compound is treated with a nitrosating agent to prepare an N-oxime compound(C). Continually, the compound(C) is cyclized with thiourea to prepare an aminothiazol compound(D), and then finally cefdinir of formula (I) is prepared by removing the carboxy protecting group.
In case cefdinir is prepared according to the reaction scheme 1, however, there can occur many problems such that the process for preparing the 7-amido compound(B) should be carried out at a temperature below -20.degree. C. under an anhydrous condition and that the isolation of the N-oxime compound(C) may cause a lot of troubles in the procedure of industrialization since the compound(C) is obtained as a solid having a syrup or a foam phase after the solvent is distilled off under reduced pressure. In addition, the aminothiazole compound(D) is obtained in a poor yield and purity and with a brownish poor color, which finally exerts a harmful influence upon the purity and color of the desired cefdinir. Further, in the reaction scheme 1, since cefdinir is synthesized through a complicated reaction consisting of 4 steps from the expensive 7-amino-3-vinyl-3-cephem-4-carboxylic acid derivative, the cost for production of cefdinir increases according as the whole reaction yield decreases.